Glass bumps on glass articles and methods of laser-induced growth

ABSTRACT

A glass article having a glass bump formed integrally thereon by laser-irradiation methods. The glass bump includes a lower region connected to an upper region by an inflection region. The lower region projects from a surface of the glass article and is defined by concavely rounded sides with a radius of curvature R 1 . The upper region includes a transition portion and a top portion. The transition portion is defined by convexly rounded sides with a radius of curvature R 2 . The transition portion connects to the lower portion via the inflection region. The upper portion connects to the transition portion and is defined by a convexly rounded top surface with a radius of curvature R 3 , which is greater than radius of curvature R 2.

BACKGROUND

The present disclosure relates to a glass bump formed on a glass articleby methods of laser-irradiating the glass article.

SUMMARY

According to one embodiment of the present disclosure, a glass articlehaving a glass bump thereon is disclosed. The glass bump comprises alower region and an upper region connected by an inflection region. Thelower region comprises a diameter D1 defined by concavely rounded sides.The lower region projects from the surface of the glass article. Thediameter D1 is the glass bump maximum diameter. The concavely roundedsides have a radius of curvature R1 and join with the glass articlesurface. The upper region of the glass bump comprises a transitionportion and a top portion. The transition portion comprises a diameterD2 defined by convexly rounded sides, diameter D2 is less than diameterD1. The convexly rounded sides have a radius of curvature R2. The topportion comprises a diameter D3 defined by a convexly rounded topsurface joining with convexly rounded sides converging from thetransition portion. The convexly rounded top surface has a radius ofcurvature R3 form about 900 microns to about 2600 microns, greater thanradius of curvature R2. Diameter D3 is less than diameter D2. Theconvexly rounded top surface is spaced apart from the glass articlesurface defining a height H of the glass bump.

According to another embodiment of the present disclosure, a glass paneincluding a glass bump formed on a surface of the glass pane by a methodis disclosed. According to the method, the glass pane surface isirradiated with laser irradiation converging through a lens from a laserirradiation source at a distance from about 1 millimeter to about 2.5millimeters away from the glass pane surface opposite the laserirradiation source. The laser irradiation locally heats and inducesgrowth of the glass bump from the glass pane. The method is free of aglass bump growth-limiting structure. The glass bump comprises a lowerregion and an upper region connected by an inflection region. The lowerregion comprises a volume V1 and a diameter D1 defined by concavelyrounded sides. The lower region projects from the surface of the glasspane. The diameter D1 is the glass bump maximum diameter. The concavelyrounded sides have a radius of curvature R1 and join with the glass panesurface. The upper region of the glass bump comprises a volume V2 havinga transition portion and a top portion. The transition portion comprisesa diameter D2 defined by convexly rounded sides, diameter D2 is lessthan diameter D1. The convexly rounded sides have a radius of curvatureR2. The top portion comprises a diameter D3 defined by a convexlyrounded top surface joining with convexly rounded sides converging fromthe transition portion. The convexly rounded top surface has a radius ofcurvature R3 from about 900 microns to about 200 microns, greater thanradius of curvature R2. Diameter D3 is less than diameter D2. Theconvexly rounded top surface is spaced apart from the glass pane surfacedefining a height H of the glass bump.

According to yet another embodiment of the present disclosure, a methodof making an article having a glass bump thereon is disclosed. The glassarticle is a glass pane with a surface. According to the method, theglass pane surface is irradiated for a time to locally heat and inducegrowth of the glass bump from the glass pane. The laser radiationconverges with a numerical aperture from about 0.01 to about 5 from alaser radiation source through a lens. The laser irradiation convergesat a distance from about 1 millimeter to about 2.5 millimeters away fromthe glass pane surface opposite the laser irradiation source. The methodis free of a glass bump growth-limiting structure. The glass bumpcomprises a lower region and an upper region connected by an inflectionregion. The lower region comprises a diameter D1 defined by concavelyrounded sides. The lower region projects from the surface of the glasspane. The diameter D1 is the glass bump maximum diameter. The concavelyrounded sides have a radius of curvature R1 and join with the glass panesurface. The upper region of the glass bump comprises a transitionportion and a top portion. The transition portion comprises a diameterD2 defined by convexly rounded sides, diameter D2 is less than diameterD1. The convexly rounded sides have a radius of curvature R2. The topportion comprises a diameter D3 defined by a convexly rounded topsurface joining with convexly rounded sides converging from thetransition portion. The convexly rounded top surface has a radius ofcurvature R3 form about 900 microns to about 2600 microns, greater thanradius of curvature R2. Diameter D3 is less than diameter D2. Theconvexly rounded top surface is spaced apart from the glass pane surfacedefining a height H of the glass bump.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be better understood, and features, aspects andadvantages other than those set forth above will become apparent whenconsideration is given to the following detailed description thereof.Such detailed description makes reference to the following drawings,wherein:

FIG. 1 is a close-up cross-sectional view of an example glass bump 50formed according to the present methods.

FIG. 2 is close-up cross-sectional view of the example glass bump 50from FIG. 1 fit with a radius of curvature equation along its concavelyrounded side wall.

FIG. 3. is close-up cross-sectional view of the example glass bump 50from FIG. 1 fit with a polynomial function along its upper region.

FIGS. 4-6 are close-up cross-sectional views of the example glass bump50 from FIG. 1 fit with a radius of curvature equation along differentsegments of one of its convexly rounded side walls.

FIGS. 7-8 are close-up cross-sectional views of the example glass bump50 from FIG. 1 fit with a radius of curvature equation along differentheights of its convexly rounded top surface.

FIG. 9 is a close-up cross-sectional view of the example glass bump 50from FIG. 1 overlaid with close-up cross-sectional views ofhemispherical glass bump 60 and conventional “flat-top” glass bump 70.

FIGS. 10-11 are close-up cross-sectional views of an exampleconventional “flat-top” glass bump 70 fit with a radius of curvatureequation along different heights of its convexly rounded top surface.

FIG. 12 is close-up cross-sectional view of an example conventional“flat-top” glass bump 70 fit with a radius of curvature equation alongits concavely rounded side wall.

FIGS. 13-15 are close-up cross-sectional views of an exampleconventional “flat-top” glass bump 70 fit with a radius of curvatureequation along different segments of one of its convexly rounded sidewalls.

FIGS. 16-17 are close-up cross-sectional views of an examplehemispherical glass bump 60 fit with a radius of curvature equationalong different heights of its convexly rounded top surface.

FIG. 18 is close-up cross-sectional view of an example hemisphericalglass bump 60 fit with a radius of curvature equation along itsconcavely rounded side wall.

FIGS. 19-21 are close-up cross-sectional views of an examplehemispherical glass bump 60 fit with a radius of curvature equationalong different segments of one of its convexly rounded side walls.

FIG. 22 is a schematic diagram of an example laser-based glass bumpforming apparatus used to form glass bumps 50 in a glass articleaccording to an exemplary embodiment.

DETAILED DESCRIPTION

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the disclosure belongs. Although any methods andmaterials similar to or equivalent to those described herein can be usedin the practice or testing of the present disclosure, the exemplarymethods and materials are described below.

A glass article of the present disclosure includes a surface and canhave any shape. In one example, the glass article can be round,spherical, curved, or flat. In another example the glass article can berelatively thick (about 10 cm) or relatively thin (about 0.1 microns).In yet another example, the glass article has a thickness between about0.5 millimeters and about 3 millimeters (e.g., 0.5, 0.7, 1, 1.5, 2, 2.5,or 3 millimeters). In one embodiment, the glass article is comprised ofa plurality of individual glass components joined or fused together(e.g., multiple square glass articles joined or fused together to alarger glass article). In an exemplary embodiment, the glass article isa glass pane 20 made of a glass material and top and bottom surfaces andan outer edge. Glass pane 20 of the present disclosure may besubstantially flat across its surfaces and may have a rectangular shape.

The glass article of the present disclosure may be formed from soda-limeglass, borosilicate glass, aluminosilicate glass, or an alkalialuminosilicate glass. Other suitable and available glasses andapplicable compositions are disclosed, for example, in U.S. PatentPublication No. 2012/0247063, the contents of which are incorporated byreference herein.

The glass article of the present disclosure comprises at least one to aplurality of glass bumps 50. In one embodiment, the glass bumps aregrown from the surface of the glass article by a laser-irradiationprocess. Glass bumps 50 of the present disclosure may be used as spacersbetween parallel, opposing panes of glass in a vacuum-insulated glass(VIG) window. In a VIG window, glass bumps 50 maintain the distancebetween the opposing glass panes that have a tendency to bow togetherunder the force of vacuum pressure there between and externalatmospheric pressure and external forces (e.g., weather). The distancebetween the parallel, opposing panes of glass in VIG window issubstantially equivalent to the heights of the glass bumps. The glassbumps of the present disclosure are configured to minimize heat transferthrough the window and reduce stress on individual glass bumps 50 andcorrespondingly on the opposing glass pane contacting glass bumps 50.

In an exemplary embodiment, the glass article (e.g., glass pane)includes a glass bump having a top surface radius of curvature greaterthan the side(s) radius of curvature. That is, the radius of curvaturefor the sides of the glass bump extending up from the glass articlesurface is smaller than the radius of curvature of the top surface. Aconvex top surface having a radius of curvature larger than the convexside walls may optimize contact between glass bump 50 and an opposingglass pane. That is, as the pressure increases between opposing panes ina VIG window (thereby transferring that force onto glass bumps 50) theopposing glass pane may deform slightly and contact a greater area ofthe glass bump top surface (e.g., 3% of the glass bump height).Likewise, when pressure decreases between opposing panes in a VIGwindow, the opposing glass pane contacts a smaller area on the glassbump top surface (e.g., 1% of the glass bump height). Accordingly, theradius of curvature along the top surface of glass bump 50 of thepresent disclosure provides benefits as compared to conventional glassbumps. In another example, glass bumps 50 may act as spacers between theglass article and other materials. In yet another example, glass bumps50 may have aesthetic advantages. Conventional glass bumps with a topsurface radius of curvature greater than 2600 microns have a large areaof contact with opposing panes in a VIG window enabling and creating alarger heat transfer area. Conventional glass bumps with a top surfaceradius of curvature less than 900 microns have a small area of contactwith opposing panes in a VIG window which may cause stress at the smallcontact area on the opposing pane and can lead to surface defects.

Glass bumps 50 may be grown out of a body portion 23 of the glassarticle and formed from the glass material making up the glass article,so as to outwardly protrude in a convex manner. Glass bumps 50 arecomprised of substantially the same glass composition as the glassarticle. In one embodiment, the glass article is comprised of aplurality of individual glass components, each glass component includingat least one locality L and/or at least one glass bump 50. The pluralityof glass bumps 50 may include any number of glass bumps including as fewas 20, 15, 10, or 5 glass bumps. In an example embodiment, glass bumps50 are regularly spaced apart on the glass article with respect to eachother. Distances between the glass bumps may be from about 1 mm (about1/25 of an inch) to about 25 centimeters (about 10 inches), or fromabout 1 centimeter (about 0.4 inches) to about 15 centimeters (about 6inches). Spacing the glass bumps closer together reduces stressconcentration on individual bumps in a VIG window. In anotherembodiment, the glass bumps are irregularly or randomly spaced apart onthe glass article with respect to each other.

Referring to FIG. 1, an example close-up cross-sectional view of anexample glass bump 50 on glass pane 20 is shown. Glass bump 50 includesa lower region 30 and an upper region 40 connected by an inflectionregion 35. Glass bump 50 has a height H50 measured from surface 24 ofglass pane 20 to a terminal point 13. Terminal point 13 is a location onglass bump 50 at the furthest distance from the surface 24 of glass pane20. In one embodiment, terminal point 13 may be an area on glass bump50. Height H50 of glass bump 50 may range from 50 microns to 200microns, or from 75 microns to 150 microns, or even from 100 microns to120 microns in exemplary embodiments. Note that if bump heights H50 aretoo small, the gap between opposing plates in a VIG window is reducedand, therefrom, a reduced vacuum space between opposing panes andreduced insulating properties. In addition, small glass bump 50 heightsH50 can lead to the appearance of optical rings due to lightinterference between closely arranged glass surfaces.

Lower region 30 of glass bump 50 projects from surface 24 of glass pane20 and is integrally formed thereon. Lower region 30 has a height H30that may extend from about 5% to about 25% of glass bump 50 height H50.Lower region 30 includes a volume V1 and a diameter D1 defined byconcavely rounded sides 31. Volume V1 may be from about 9.42×10⁵ cubicmicrons to about 2.51×10⁷ cubic microns. Diameter D1 may be the maximumdiameter D_(M) of glass bump 50. That is, maximum diameter D_(M) is thedistance between the points A and B where concavely rounded sides 31terminate and join with surface 24 of glass pane 20. Maximum diameterD_(M) may be from about 400 microns to about 800 microns, or even 500microns to 700 microns. Glass bumps 50 with maximum diameter D_(M)smaller than 400 microns may have a top surface with a radius ofcurvature less than 750 microns which increases stress concentration onopposing glass panes in a VIG window. Glass bumps 50 with diameter D1larger than 800 microns may be visible when used between glass panes ina VIG window.

Concavely rounded sides 31 of lower region 30 include a radius ofcurvature R1. Concave radius of curvature R1 may be from about 25microns to about 100 microns. Radius of curvature R1 may vary slightlywithin the disclosed range at different locations around glass bump 50.Radius of curvature R1 is configured such that glass bump 50 projectsfrom glass pane 20 surface 24 so as not to exceed the disclosed rangefor diameter D1 and to maintain a top surface radius of curvature asdisclosed herein. FIG. 2 illustrates a close-up cross-sectional view ofan example glass bump 50. Example glass bump 50 height H50 is about 168microns with maximum diameter D_(M) at about 586 microns. As shown inFIG. 2, radius of curvature R1 is about 33 microns measured fromcoordinate (1 micron, 1 micron) C to coordinate (22 microns, 13 microns)D along one concavely rounded side 31 of glass bump 50.

Referring back to FIG. 1, inflection region 35 of glass bump 50 connectslower region 30 and upper region 40. Upper region 40 includes a volumeV2 having a transition portion 41 and a top portion 42. Upper region 40has a height H40 that may extend from about 75% to about 95% of glassbump 50 height H50. Volume V2 may be from about 1.41×10⁷ cubic micronsto about 9.55×10⁷ cubic microns. In one embodiment, volume V2 is greaterthan volume V1 in glass bump 50. In another embodiment, volume V2 isgreater than volume V1 by at least 5%, but up to 50%. In anotherembodiment, volume V2 extends from about 85% to about 92% of glass bump50 diameter D1. In yet another embodiment, a lateral profile (i.e., thecross-sectional view shown in FIG. 1) of upper region is represented bya 4^(th) power polynomial function having the formula y=−1.94×10⁻⁸x⁴+−5.76×10⁻⁴ x²+168.47 with a coefficient of determination form about0.95 to about 0.999. The coefficients for this 4^(th) power polynomialfunction may vary by up to 5%. FIG. 3 illustrates this polynomialfunction fit to a portion of the upper region an example glass bump 50of the present disclosure with a coefficient of determination of about0.999. The polynomial function is fit to the lateral profile of upperregion 40 of an example glass bump 50 from coordinate E at (55 microns,78 microns) to coordinate F at (531 microns, 78 microns) along thelateral profile of glass bump 50. That is, the polynomial function mayfit at least 40%, but up to 60%, of the upper region of the lateralprofile of glass bump 50.

Referring back to FIG. 1, transition portion 41 of upper region 40includes a diameter D2 defined by convexly rounded sides 32. Diameter D2may extend from about 33% to about 85% of the maximum diameter D_(M) ofglass bump 50. Convexly rounded sides 32 join with concavely roundedsides 31 extending up from lower region 30 at inflection region 35.Convexly rounded sides 32 have a radius of curvature R2. Convex radiusof curvature R2 may be from about 175 microns to about 850 microns, orabout 200 microns to about 500 microns, and may vary slightly within thedisclosed range at different locations around glass bump 50. FIGS. 4-6illustrate a close-up cross-sectional view of example glass bump 50. Ineach of FIGS. 4-6, glass bump 50 is fit with a radius of curvatureequation along one of convexly rounded side walls 32 in transitionportion 41 with coefficient of determination (i.e., r-squared) greaterthan 0.999. In FIG. 4, radius of curvature R2 is about 483 micronsmeasured from coordinate G at (56 microns, 76 microns) to coordinate Hat (64 microns, 84 microns) along one of convexly rounded side walls 31of glass bump 50. In FIG. 5, radius of curvature R2 is about 201 micronsmeasured from coordinate I at (115 microns, 130 microns) to coordinate Jat (133 microns, 140 microns) along one of convexly rounded side walls31 of glass bump 50. In FIG. 6, radius of curvature R2 is about 399microns measured from coordinate K at (179 microns, 158 microns) tocoordinate L at (198 microns, 162 microns) along one of convexly roundedside walls 31 of glass bump 50.

Radius of curvature R2 may be measured over at least 5 microns or 5% ofglass bump 50 height H50. Alternatively, R2 may be measured at or over50% glass bump 50 height H50. Diameter D2, measured between convexlyrounded sides 32, may be from about 132 microns to about 680 microns.Diameter D2 of transition portion 41 decreases by about 15% to about 65%from inflection region 35 to top portion 42. Diameter D2 is less thandiameter D1 since the total diameter of glass bump 50 graduallydecreases from lower region to transition portion 41.

Referring back to FIG. 1, top portion 42 includes a diameter D3 and isdefined by a convexly rounded top surface 43. Convexly rounded topsurface 43 is spaced apart from glass pane 20 surface 24 defining heightH50 of glass bump 50. Convexly rounded top surface 43 may extend fromabout 1% to about 3% of glass bump 50 height H50. In other embodiments,convexly rounded top surface 43 may extend from about 15% to about 35%of maximum diameter D_(M), or about 20% to about 33% of maximum diameterD_(M). Convexly rounded top surface 43 joins with convexly rounded sides32 converging from transition portion 41. Convexly rounded top surface43 has a convex radius of curvature R3 from about 900 microns to about2600 microns, or about 950 microns to about 2000 microns. FIGS. 7-8illustrate a close-up cross-sectional view of example glass bump 50. InFIGS. 7-8, glass bump 50 is fit with a radius of curvature equationalong convexly rounded top surface 43 in top portion 42.

In FIG. 7, radius R3 is about 2564 microns measured from coordinate M at(225 microns, 166 microns) to coordinate N at (361 microns, 166 microns)along convexly rounded top surface 43 of glass bump 50. Radius R3 fromcoordinate M to N extends 1% of height H50 of glass bump 50. In FIG. 8,convex radius R3 is about 1075 microns measured from coordinate 0 at(211 microns, 163 microns) to coordinate P at (375 microns, 163 microns)along convexly rounded top surface 43 of glass bump 50. Radius R3 fromcoordinate 0 to P extends 3% of height H50 of glass bump 50. In FIGS.7-8, convexly rounded top surface 43 includes slight imperfections or“noise” along rounded top surface 43 created by limitations within theoptical scanning profilometer used to show the lateral profile of glassbump 50. Accordingly, close fit curves have a coefficient ofdetermination (i.e., r-squared) greater than 0.55, or even 0.85. Inalternative embodiments, convexly rounded top surface 43 includes aslight concave area with a concave radius of curvature R4 greater thanabout 3500 microns and less than 5000 microns at or around terminalpoint 13.

Radius of curvature R3 is configured with a radius of curvature suchthat contact between opposing glass panes in a VIG window is sufficientto alleviate stress on individual glass bumps 50 and the opposing glasspanes, and also limited to minimize contact heat transfer between theopposing panes through glass bump 50. Radius of curvature R3 is suchthat is can be formed by a laser irradiation process of the presentdisclosure without the use of a growth-limiting structure. Thelaser-irradiation process of the present disclosure, free of agrowth-limiting structure, presents significant time savings for growingglass bumps 50 with a large radius of curvature (i.e., from 900 micronsto 2600 microns) on its top surface as compared to conventional methods.Specifically, the need to align the glass article relative to thegrowth-limiting structure before growing glass bump 50 vialaser-irradiation is eliminated.

In an exemplary embodiment, convex radius of curvature R3 is greaterthan convex radius of curvature R2. In another embodiment, R3 is greaterthan R2 by about 80% to about 300%, or about 100% to about 250%. In yetanother embodiment, convex radius of curvature R3 is greater thanconcave radius of curvature R1. Diameter D3, measured as a chord onconvexly rounded top surface 43, is less than diameter D2. Diameter D3at its maximum may be from about 132 microns to about 264 microns.Diameter D3 decreases incrementally to a point at or around terminationpoint 13.

Transition portion 41 and top portion 42 are integrally formed together.Further, inflection region 35 connects the lower region 30 and upperregion 40 at transition portion 41. Inflection region 35 may be definedby sides without a radius of curvature (i.e., flat or perpendicular tosurface 24). In one embodiment, inflection region 35 is a 2-dimensionalarea (e.g., a plane). In another embodiment, inflection region 35 is avolume V4 extending at most about 5% of glass bump 50 height H50.

Glass bump 50 as described above and according to the present disclosureis different than conventional glass bumps grown according toconventional methods. Referring to FIG. 9, a close-up cross-sectionalview of example glass bump 50 of the present disclosure is illustrated.Also provided are conventional glass bumps 70 and 60 manufactured bymethods different than the present disclosure. Close-up cross-sectionalview of glass bump 70 in FIG. 9 is grown according to conventionallaser-irradiation methods including a growth-limiting structure. Forexample, U.S. Patent Publication No. US 2013/0321903A1 provides a methodof growing a plurality of growth-limited glass bump 70 which has “asubstantially flat top portion.”

Glass bump 70 in FIG. 9 is further illustrated in FIGS. 10-15. Exampleglass bump 70 in FIGS. 10-15 has a height H70 of about 128 microns and abase diameter DB70 of about 562 microns. As shown in FIG. 10, glass bump70 has a radius of curvature R5 of about 4142 microns measured fromcoordinate Q at (189 microns, 128 microns) to coordinate R at (401microns, 128 microns) along glass bump 70 top surface. Radius R5 fromcoordinate Q to R extends 1% of height H70 of glass bump 70. As shown inFIG. 11, glass bump 70 has a radius of curvature R5 of about 3069microns measured from coordinate S at (170 microns, 125 microns) tocoordinate T at (421 microns, 125 microns) along glass bump 70 topsurface. Radius R5 from coordinate S to T extends 3% of height H70 ofglass bump 70. As shown in FIG. 12, glass bump 70 has a radius ofcurvature R7 of about 40 microns measured from coordinate U at (1micron, 1 micron) to coordinate V at (32 microns, 14 microns) along oneof its concavely rounded sides. As shown in FIG. 13, glass bump 70 has aradius of curvature R8 of about 4047 microns measured from coordinate Wat (53 microns, 58 microns) to coordinate X at (59 microns, 63 microns)along on of its convexly rounded sides. As shown in FIG. 14, glass bump70 has a radius of curvature R8 of about 2977 microns measured fromcoordinate Y at (100 microns, 101 microns) to coordinate Z at (105microns, 105 microns) along one of its convexly rounded sides. As shownin FIG. 15, glass bump 70 has a radius of curvature R8 of about 643microns measured from coordinate AA at (150 microns, 120 microns) tocoordinate BB at (160 microns, 124 microns) along one of its convexlyrounded sides. In FIGS. 10-15, convexly rounded top surface includesslight imperfections or “noise” along convex radius of curvature R5created by limitations within the optical scanning profilometer used toshow the lateral profile of glass bump 70.

Referring again to FIG. 9, close-up cross-sectional view ofhemispherical glass bump 60 is shown which is grown according to otherconventional laser-irradiation methods. Glass bump 60 in FIG. 9 isfurther illustrated in FIGS. 16-21. Example glass bump 60 in FIGS. 16-21have a height H60 of about 188 microns and a base diameter DB60 of about666 microns. As shown in FIG. 16, glass bump 60 has a radius ofcurvature R6 of about 680 microns measured from coordinate CC at (286microns, 186 microns) to coordinate DD at (382 microns, 186 microns)along glass bump 60 top surface. Radius R6 from coordinate CC to DDextends 1% of a height H60 of glass bump 60. As shown in FIG. 17, glassbump 60 has a radius of curvature R6 of about 656 microns measured fromcoordinate EE at (249 microns, 182 microns) to coordinate FF at (418microns, 182 microns) along glass bump 60 top surface. Radius R6 fromcoordinate EE to FF extends 3% of height H60 of glass bump 60. As shownin FIG. 18, glass bump 60 has a radius of curvature R9 of about 30microns measured from coordinate GG at (6 microns, 1 micron) tocoordinate HH at (31 microns, 12 microns) along one of its concavelyrounded sides. As shown in FIG. 19, glass bump 60 has a radius ofcurvature R10 of about 398 microns measured from coordinate II (71microns, 85 microns) to coordinate JJ (77 microns, 93 microns) along oneof its convexly rounded sides. As shown in FIG. 20, glass bump 60 has aradius of curvature R10 of about 273 microns measured from coordinate KK(143 microns, 148 microns) to coordinate LL (149 microns, 152 microns)along one of its convexly rounded sides. As shown in FIG. 21, glass bump60 has a radius of curvature R10 of about 32 microns measured fromcoordinate MM (223 microns, 176 microns) to coordinate NN (229 microns,180 microns) along one of its convexly rounded sides.

Table 1 below provides a comparison of various radii of curvature ofglass bump 50 of the present disclosure against radii of curvature ofglass bumps 60 and 70 formed according to conventional methods. Asprovided in Table 1, radius R1 of glass bump 50 is compared to similarradius R9 and R7 of glass bumps 60 and 70, respectively. Also, radius R2of glass bump 50 is compared to similar radius R10 and R8 of glass bumps60 and 70, respectively. Further, radius R3 of glass bump 50 is comparedto similar radius R6 and R5 of glass bumps 60 and 70, respectively.

TABLE 1 Comparison of Glass Bump 50 of the present disclosure andConventional Glass Bumps 60 and 70. Glass Glass Glass bump 50 bump 60bump 70 Concave radius of R1 R9 R7 curvature for the (25 microns- (25microns- (25 microns- concavely rounded 100 microns) 50 microns) 50microns) sides Convex radius of R2 R10 R8 curvature for the (200microns- (233 microns- (643 microns- convexly rounded 500 microns) 398microns) 4047 microns) sides Convex radius of R3 R6 R5 curvature for the(900 microns- (650 microns- (3069 microns- convexly rounded 2600microns) 680 microns) 4142 microns) top surface (over 1- 3% of the glassbump height H) Concave radius of R4 N/A N/A curvature for the (3500microns- concave area on the 5000 microns) convexly rounded top surface

The convex radius of curvature R3 for the convexly rounded top surface(at 1-3% of top portion of glass bump height H50), R3, for glass bump 50is 900-2600 microns. This radius of curvature R3 optimizes the contactbetween glass bump 50 and an opposing glass pane in a VIG window duringincreasing and decreasing pressure from the opposing pane on theconvexly rounded top surface. As shown in Table 1 and described above,radius of curvature R3 for glass bump 50 is novel and inventive ascompared to conventional glass bumps 60 and 70 used, for example, in VIGwidows.

In one embodiment of the present disclosure, glass bumps 50 are formedby photo-induced absorption. Photo-induced absorption includes a localchange of the absorption spectrum of a glass article resulting fromlocally exposing (irradiating), or heating, the glass article withradiation (i.e., laser irradiation). Photo-induced absorption mayinvolve a change in adsorption at a wavelength or a range ofwavelengths, including but not limited to, ultra-violet, nearultra-violet, visible, near-infrared, and/or infrared wavelengths.Examples of photo-induced absorption in the glass article include, forexample, and without limitation, color-center formation, transient glassdefect formation, and permanent glass defect formation. Laserirradiation dose is a function of laser power P and exposure time.

FIG. 22 is a schematic diagram of an example laser-based apparatus(“apparatus 100”) used to form glass bumps 50 in the glass article(e.g., glass pane 20). Apparatus 100 may include a laser 110 arrangedalong an optical axis A1. Laser 110 emits a laser beam 112 having powerP along the optical axis A1. In an example embodiment, laser 110operates in the ultraviolet (UV) region of the electromagnetic spectrum.Laser irradiation dose is a function of laser beam 112 power P and anexposure time.

Apparatus 100 also includes a focusing optical system 120 that isarranged along optical axis A1 and defines a focal plane P_(F) thatincludes a focal point FP. In an example embodiment, focusing opticalsystem 120 includes, along optical axis A1 in order from laser 110: acombination of a defocusing lens 124 and a first focusing lens 130(which in combination forms a beam expander 131), and a second focusinglens 132. In an alternative embodiment, focusing optical system 120includes, along optical axis A1 in order from laser 110: a beam expander131 and a second focusing lens 132. Beam expander may be configured toincrease or decrease the diameter of laser beam 112 by two times or fourtimes to create collimated laser beam 112C with an adjusted diameterD_(B).

In an example embodiment, defocusing lens 124 has a focal length fD=−5cm, first focusing lens 130 has a focal length fC1=20 cm, and secondfocusing lens 132 has a focal length fC2=3 cm and a numerical apertureNAC2=0.3. In an example embodiment, defocusing lens 124 and first andsecond focusing lenses 130 and 132 are made of fused silica and includeanti-reflection (AR) coatings. In another embodiment, focusing lens 130and/or 132 are aspherical lenses. In yet another embodiment, secondfocusing lens 132 has a numerical aperture NAC2=0.5. Alternate exampleembodiments of focusing optical system 120 include mirrors orcombinations of mirrors and lens elements configured to produce focusedlaser beam 112F from laser beam 112.

Apparatus 100 also includes a controller 150, such as a lasercontroller, a microcontroller, computer, microcomputer or the like,electrically connected to laser 110 and adapted to control the operationof the laser. In an example embodiment, a shutter 160 is provided in thepath of laser beam 112 and is electrically connected to controller 150so that the laser beam can be selectively blocked to turn the laser beam“ON” and “OFF” using a shutter control signal SS rather than turninglaser 110 “ON” and “OFF” with a laser control signal SL.

Prior to initiating the operation of apparatus 100, the glass article isdisposed relative to the apparatus. Specifically, the glass article isdisposed along optical axis A1 so that a surface of the glass article issubstantially perpendicular to the optical axis A1. In an exampleembodiment, glass pane 20, including a front surface 22 and back surface24, is disposed relative to optical axis A1 so that back glass panesurface 24 is slightly axially displaced from focal plane PF in thedirection towards laser 110 (i.e., in the +Z direction) by a distanceDF. In methods according to the present disclosure, distance DF mayrange from 0.1 millimeters to 3 millimeters. In an exemplary embodiment,distance DF may range from about 1 millimeter to about 2.5 millimeters.In yet another embodiment of forming glass bump 50, numerical apertureNAC2=0.3. In another example embodiment, glass pane 20 has a thicknessTG in the range 0.5 millimeters≦TG≦6 millimeters. Using theseparameters, glass bump 50 of the present disclosure is capable of beinggrown from glass pane 20. Conventional methods of forming glass bumpshave not produced a glass bump with a top surface (along 1-3% of the topportion of its height) with a radius of curvature greater than 750microns, or even, 900 microns, without the use of a growth limitingstructure. Accordingly, when using a growth limiting structure, glassbumps 70 have a top surface radius of curvature R5 greater than 3000microns. Accordingly, the above numerical aperture NAC2 and DF valuesresult in glass bump 50 with novel geometric properties.

In an example method of operating apparatus 100, laser 110 may beactivated via control signal SL from controller 150 to generate laserbeam 112. If shutter 160 is used, then after laser 110 is activated, theshutter is activated and placed in the “ON” position via shutter controlsignal SS from controller 150 so that the shutter passes laser beam 112.Laser beam 112 is then received by focusing optical system 120, anddefocusing lens 124 therein causes the laser beam to diverge to form adefocused laser beam 112D. Defocused laser beam 112D is then received byfirst focusing lens 130, which is arranged to form an expandedcollimated laser beam 112C from the defocused laser beam. Collimatedlaser beam 112C is then received by second focusing lens 132, whichforms a focused laser beam 112F. Focused laser beam 112F passes throughglass pane 20 and forms a spot S along optical axis A1 at focal pointFP, as mentioned above, is at a distance D_(F) from glass pane backsurface 24 and thus resides outside of body portion 23. The intersectionbetween the converging laser beam 112F and glass pane 20 front surface22 and back surface 24 is referred to herein as a locality L. Laser beam112F may be focused on a different area of glass pane 20 to form anotherlocality L.

A portion of focused laser beam 112F is absorbed as it passes throughglass pane 20 (at locality L) due to the aforementioned photo-inducedabsorption in the glass pane. This serves to locally heat glass pane 20at locality L. The amount of photo-induced absorption may be relativelylow, e.g., about 3% to about 50%. The glass bump begins to form as alimited expansion zone is created within glass pane 20 body portion 23in which a rapid temperature change induces an expansion of the glass.Since the expansion zone is constrained by unheated (and thereforeunexpanded) regions of glass surrounding the expansion zone, the moltenglass within the expansion zone is compelled to relieve internalstresses by expanding/flowing upward, thereby forming glass bump 50. Iffocused laser beam 112F has a circularly symmetric cross-sectionalintensity distribution, such as a Gaussian distribution, then the localheating and the attendant glass expansion occurs over a circular regionin glass pane body 23, and the resulting glass bump 50 may besubstantially circularly symmetric.

The aforementioned process can be repeated at different locations (e.g.,localities L) in the glass pane to form a plurality (e.g., an array) ofglass bumps 50 in glass pane 20. In an example embodiment, apparatus 100includes an X-Y-Z stage 170 electrically connected to controller 150 andconfigured to move glass pane 20 relative to focused laser beam 112F inthe X, Y and Z directions, as indicated by large arrows 172. This allowsfor a plurality of glass bumps 50 to be formed by selectivelytranslating stage 170 via a stage control signal ST from controller 150and irradiating different locations in glass pane 20. In another exampleembodiment, focusing optical system 120 is adapted for scanning so thatfocused laser beam 112F can be selectively directed to locations inglass pane 20 where glass bumps 50 are to be formed.

As used herein, the singular forms “a,” “an,” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to a “metal” includes examples having two or moresuch “metals” unless the context clearly indicates otherwise.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, examples include from the one particular value and/or to theother particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is no way intended thatany particular order be inferred.

It is also noted that recitations herein refer to a component of thepresent invention being “configured” or “adapted to” function in aparticular way. In this respect, such a component is “configured” or“adapted to” embody a particular property, or function in a particularmanner, where such recitations are structural recitations as opposed torecitations of intended use. More specifically, the references herein tothe manner in which a component is “configured” or “adapted to” denotesan existing physical condition of the component and, as such, is to betaken as a definite recitation of the structural characteristics of thecomponent.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Sincemodifications combinations, sub-combinations and variations of thedisclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and their equivalents.

What is claimed is:
 1. A glass article comprising: a glass surfacehaving a glass bump thereon, wherein the glass bump comprises: a lowerregion comprising a diameter D1 defined by concavely rounded sides,wherein the lower region projects from the surface of the glass article,wherein diameter D1 is the glass bump maximum diameter, wherein theconcavely rounded sides have a radius of curvature R1 and join with theglass article surface; an inflection region connecting the lower regionof the glass bump and an upper region of the glass bump; the upperregion of the glass bump comprising a transition portion and a topportion; the transition portion comprising a diameter D2 defined byconvexly rounded sides, wherein the convexly rounded sides have a radiusof curvature R2, wherein diameter D2 is less than diameter D1; and thetop portion comprising a diameter D3 defined by a convexly rounded topsurface, the convexly rounded top surface joining with the convexlyrounded sides converging from the transition portion, wherein theconvexly rounded top surface has a radius of curvature R3 from about 900microns to about 2600 microns which is greater than the radius ofcurvature R2, wherein diameter D3 is less than diameter D2, wherein theconvexly rounded top surface is spaced apart from the glass articlesurface defining a height H of the glass bump.
 2. The glass article ofclaim 1 wherein the radius of curvature R1 of concavely rounded sides ofthe lower region is from about 25 microns to about 100 microns.
 3. Theglass article of claim 1 wherein diameter D1 of the lower region is fromabout 400 microns to about 800 microns.
 4. The glass article of claim 1wherein the radius of curvature R2 of the convexly rounded sides of thetransition portion is from about 175 microns to about 950 microns overat least 5% of the glass bump height H.
 5. The glass article of claim 1wherein diameter D2 of the transition portion decreases from theinflection region to the top portion by about 15% to about 65%.
 6. Theglass article of claim 1 wherein diameter D2 of the transition portionis from about 132 microns to about 680 microns.
 7. The glass article ofclaim 1 wherein diameter D3 of the top portion is from about 132 micronsto about 264 microns.
 8. The glass article of claim 1 wherein glass bumpheight H is from about 50 microns to about 200 microns.
 9. The glassarticle of claim 1 wherein a lateral profile of the upper region has apolynomial function of the formulay=−1.94×10⁻⁸ x ⁴+−5.76×10⁻⁴ x ²+168.47 and a coefficient ofdetermination from about 0.95 to about 0.999.
 10. The glass article ofclaim 1 wherein the convexly rounded top surface of the top portionincludes a concave area.
 11. The glass article of claim 1 wherein thelower region is from about 5% to about 25% of glass bump height H. 12.The glass article of claim 1 wherein the upper region is from about 75%to about 95% of glass bump height H.
 13. The glass article of claim 1wherein the top portion is from about 1% to about 3% of glass bumpheight H.
 14. A glass pane including a glass bump formed on a surface ofthe glass pane by a method comprising: irradiating the glass panesurface with laser radiation converging through a lens from a laserradiation source, wherein the laser radiation converges at a distancefrom about 1 millimeter to about 2.5 millimeters away from the glasspane surface opposite the laser radiation source, wherein the laserradiation locally heats and induces growth of the glass bump from theglass pane, wherein the method is free of a glass bump growth-limitingstructure, wherein the glass bump comprises: a lower region comprising avolume V1 with a diameter D1 defined by concavely rounded sides, whereinthe lower region projects from the glass pane surface, wherein diameterD1 is the glass bump maximum diameter, wherein the concavely roundedsides have a radius of curvature R1 and join with the glass panesurface; an inflection region connecting the lower region of the glassbump and an upper region of the glass bump; the upper region comprisinga volume V2 having a transition portion and a top portion; thetransition portion comprising a diameter D2 defined by convexly roundedsides, wherein the convexly rounded sides have a radius of curvature R2,wherein diameter D2 is less than diameter D1; and the top portioncomprising a diameter D3 defined by a convexly rounded top surface, theconvexly rounded top surface joining with the convexly rounded sidesconverging from the transition portion, wherein the convexly rounded topsurface has a radius of curvature R3 from about 900 microns to about2600 microns which is greater than the radius of curvature R2, whereindiameter D3 is less than diameter D2, wherein the convexly rounded topsurface is spaced apart from the glass pane surface defining a maximumheight H of the glass bump.
 15. The glass pane of claim 14 whereinvolume V1 of the lower region of the glass bump is from about 9.42×10⁵cubic microns to about 2.51×10⁷ cubic microns.
 16. The glass pane ofclaim 14 wherein volume V2 of the upper region of the glass bump is fromabout 1.41×10⁷ cubic microns to about 9.55×10⁷ cubic microns.
 17. Theglass pane of claim 14 wherein volume V2 of the glass bump is greaterthan volume V1 of the glass bump.
 18. The glass pane of claim 14 whereinvolume V2 of the glass bump is from about 85% to about 92% of diameterD1.
 19. The glass pane of claim 14 wherein the radius of curvature R3 ofthe convexly rounded top surface is greater than the radius of curvatureR1 for the concavely rounded sides of the lower region.
 20. A method ofmaking the article of claim 1, wherein the article is a glass pane, themethod comprising: irradiating the glass pane surface with laserradiation for a time to locally heat and induce growth of the glass bumpfrom the glass pane, wherein the laser radiation is converging with anumerical aperture from about 0.01 to about 0.5 from a laser radiationsource through a lens, wherein the laser radiation converges at adistance from about 1 millimeter to about 2.5 millimeters away from theglass pane surface opposite the laser irradiation source, wherein themethod is free of a glass bump growth-limiting structure.